The following patents and/or commonly assigned patent applications are hereby incorporated herein by reference:
This invention relates to the field of optical communications, more particularly to switches used in fiber-optic networks.
Optical networks use modulated light to enable clear, rapid communication between two points. The bandwidth and efficiency provided by optical communication systems is well known. A single fiber is able to carry a great deal of information over a tremendous distance. Practical communication systems utilize large numbers of fibers networked together to form a communication web that provides at least one path between any two points on the network. Configuring the network to connect any two points requires a large number of switches.
One method of coupling optical fibers converts the optical signal carried by the input fiber to electrical signals and uses the electrical signal modulate another light beam that is transmitted along the second fiber. This method is much slower than simply switching the optical beam and may introduce noise into the transmitted optical signal. Purely optical switching, in which the optical beam from a first fiber is coupled directly to a second fiber without significant loss, is much faster and more efficient and is therefore desired.
Several types of optical switches have been developed. Some use mechanical means to physically align the input and output fibers. These mechanical switches typically are slow, large, and very expensive. Micromirror based switches either use analog mirrors, which have difficulty maintaining alignment over long periods of time, or are difficult to arrange in matrix switches larger than 1xc3x972. What is needed is an improved optical switch that is very quick to configure, does not require the light beam to be converted to electricity, and allows connection between an input and a large number of outputs.
Objects and advantages will be obvious, and will in part appear hereinafter and will be accomplished by the present invention that provides a method and system for switchably coupling optical fiber communications using a micromirror device. One embodiment of the claimed invention provides an optical switch. The optical switch comprises: at least one input fiber, at least one output fiber, a retro-reflective surface, and a mirror array. Each input fiber defining an input optical axis and having an exit end. Each output fiber defining an output optical axis and having an entrance end. The retro-reflective surface being between exit and entrance ends. The mirror array defines an x-y plane substantially parallel to said retro-reflective surface, and is comprised of at least one mirror on each input and output optical axis. The mirrors on the input optical axes are operable to rotate about a single axis parallel to the x-y plane to deflect light from each input fiber to at least one intermediate spot on the retro-reflector. The mirrors on the output optical axes are operable to reflect light from at least one of the intermediate spots of the retro-reflector to an associated output fiber sharing the output axis. Variations of this optical switch include embodiments with focusing elements between at least one fiber and the mirror array, and embodiments using groups of mirrors in place of single mirrors associated with each fiber.
According to another embodiment of the present invention an optical switch is disclosed. The optical switch comprises: at least one input fibers, at least one output fiber, a retro-reflective surface, and a mirror array. Each input fiber defines an input optical axis and has an exit end. Each output fiber defines an output optical axis and has an entrance end. The retro-reflective surface is between the exit and entrance ends of the fibers, and substantially parallel to the mirror array. The mirror array is comprised of at least one mirror on each said input optical axis and said output optical axis and at least one intermediate mirror. The mirrors on the input optical axes are operable to rotate about a single axis parallel to the plane of the mirror array. The mirrors deflect light from each input fiber to at least one intermediate spot on the retro-reflector. The mirrors on the output optical axes are operable to reflect light from at least one of the intermediate spots of the retro-reflector to an associated output fiber sharing the output axis. The intermediate mirrors are operable to rotate about a single axis parallel to said plane of the mirror array to deflect light from at least one intermediate spot to at least one other intermediate spot. Variations of this optical switch include embodiments with focusing elements between at least one fiber and the mirror array, and embodiments using groups of mirrors in place of single mirrors associated with each fiber.
The disclosed invention has the advantage of providing low-cost, manufacturable switches that provide efficient switching of optical signals propagated on optical fibers using readily available single axis torsion mirrors.